<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>

        .box{width: 100px;height: 100px;background: red;}

    </style>
</head>
<body>
    认识javascript
    <div class="box" onclick="alert('hello')"></div>
</body>
<script src="./index.js">

    alert('你好')

</script>
</html>